1. Field of the Invention
The present invention relates generally to surgical instruments, and more particularly to cannulas or sleeves employed in endoscopic surgery.
2. Background Information
Surgical sleeves or cannulas are conventionally used in endoscopic or laparoscopic surgery to facilitate passage of surgical instruments such as endoscopes, clip appliers, and the like into a body cavity, usually the abdominal cavity. The sleeve is inserted through an incision made in the abdominal wall and into the body cavity, where it remains until the surgery is concluded. Various surgical instruments then are passed through the sleeve and into the body cavity to accomplish surgical procedures. Often, the body cavity is insufflated with an inert gas, such as CO.sub.2, to lift the abdominal wall to facilitate viewing of the interior of the body cavity with the endoscope.
A recent improvement to these surgical sleeves is to provide the sleeve with an expandable member that is selectively expanded within the body cavity to prevent inadvertent full or partial withdrawal of the sleeve from the body cavity. Such surgical sleeves are disclosed in commonly assigned U.S. Pat. Nos. 5,122,122 and 5,217,451. The sleeves disclosed in those patents employ an expandable member in the form of an expandable hinge formed by a plurality of longitudinal slits made in the outer sleeve. Relative movement between inner and outer sleeves causes the expandable hinge structure to expand radially, wherein the sleeve resists withdrawal from the body cavity.
As presently manufactured, the expandable hinge structure is formed integrally with the outer sleeve portion of the sleeve assembly. Because the outer sleeve portion is generally tubular and several inches long, such sleeves are rather cumbersome and expensive to manufacture.
Surgical sleeves such as those in disclosed in U.S. Pat. Nos. 5,122,122 and 5,217,451 are used with surgical instruments of varying diameter. Typically, the sleeve is chosen to have an interior diameter large enough to accommodate the largest diameter instrument to be used with the sleeve. The sleeves are provided with seals that obstruct the inner diameter of the sleeve to prevent escape of insufflation gas from the body cavity, whether an instrument is present in the sleeve or not. Such seals typically include a lip seal for the sealing the interior passage of the sleeve when an instrument is not present in the sleeve, and an outer diameter (O.D.) seal to seal against the outer diameter of an instrument present in the sleeve. By necessity, the O.D. seal can only seal against instruments having outer diameters within a relatively small range, e.g., the O.D. seal in an 11 mm sleeve can seal against instruments having outer diameters between about 10 and 11 mm, but not against instruments much smaller than 10 mm in diameter. If a smaller diameter instrument is to be used with a sleeve, an auxiliary O.D. seal must me employed. These auxiliary O.D. seals are commonly known as "reducers," and as relatively small and separate parts, are clumsy in operation and represent one more item for operating room personnel to account for during surgical procedures.
A trocar or obturator is commonly used with a surgical sleeve to form the incision through which the sleeve is inserted into the body cavity. A trocar generally is a sharpened, pointed instrument that is placed in the surgical sleeve with the sharpened, pointed end protruding therefrom. The sleeve and trocar together are pressed against the exterior of the abdomen and the pointed end of the trocar forms the incision through which the sleeve is inserted. One such trocar is disclosed in commonly assigned U.S. Pat. No. 5,224,951. That trocar generally comprises a tubular, metallic sleeve having a sharpened and pointed end and a coring prevention means disposed in the sharpened end to prevent coring of tissue. Such a design is costly to manufacture because it requires that the cylindrical outer member, which extends the length of the trocar, be formed entirely of expensive surgical stainless steel.
A need exists, therefore, for a surgical sleeve and trocar that are modular in construction and thus less costly to manufacture. Additionally, a need exists for a surgical sleeve provided with an integral reducer capable of sealing against surgical instruments having a variety of outer diameters.